1. Field of the Invention
The present invention is directed to a device for conveying a sheet between stations of the platen press with a dwell period at each station.
2. Prior Art
To intermittently convey sheets through various stations of a platen press with a dwell period at each station, conveying device comprising a pair of endless chains having gripper bars extending therebetween have been utilized. The endless chains are moved by a drive shaft having driving sprockets engaging each of the chains which are supported in their paths by at least one additional driven or idler sprocket. Although the driving sprockets intermittently advance the chains, the inertia forces developed by the movement of the endless chain conveyor have been compensated during a dwell period of the drive shaft by applying a braking action from a pneumatic brake device directly acting on the drive shaft of the drive sprockets. An example of such a device is described in Swiss Patent No. 323,629 dated Aug. 15, 1957. Although a device for conveying sheets between stations with a dwell period provided with a brake as described in this manner is a reliable system, it has certain short comings such as a poor adaptability for high speed operation and it requires continual resetting and adjustments of the braking device for proper inertia compensation.